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Re: O.T. optimising file placement

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Martin Gregorie wrote:
> Unlike some, I take a good deal of interest in what my machines are up
> to, so I was quoting what I see using top on my Linux systems. During
> normal operation there is very little activity on my laptop except from
> the programs I'm actively using unless, as you say, logwatch/smartd/
> rkhunter/updatedb get run by atd, but on a reasonably quick machine they
> don't run for long.
>
> Of course, the house server is a different case, since it has several
> 24/7 services on it, but again its only heavy, continuous disk activity
> is overnight when it runs backups/logwatch/smartd/updatedb. Apart from
> that requests that wake up Postfix/Spamassassin/Apache/or ftpd/sshd are
> pretty sporadic and the disk LED flashes are best described as
> intermittent.

Sounds like disk optimizations would help that system.

> The longest continuously busy time on either machine is during backups
> and even there there precious little contention since rsync or tar+gzip
> since the only stuff being written to the disk its reading from are
> backup logs. Same applies to software update sessions. To the best of my
> knowledge (and watching top) none of yum, rpm, tar, gzip or rsync are
> multi-threaded: rsync is probably using poll() based async i/o but from
> top and observed behaviour none of the others seem to do that. In fact
> the only long-running programs on my systems that I know to be multi-
> threaded are Apache, Postgres, SA and Postfix.

Now /that/ is objective evidence.

In your particular case you have no need of optimization of your disk 
processes. You don't mention it but by omission I will grant you that virtual 
memory on your system does not seriously contend for disk either. But a 
typical consumer scenario is to listen to a stream while surfing the web on 
Windows with several chat windows open, causing multiple disk IO ops on a 
constant basis of themselves and also putting pressure on virtual memory. Even 
such a single-user system can benefit from elevator seeking and on-disk buffers.

Consider also that burstiness of demand does not argue against the need for 
optimization, really. During bursts the optimization helps, and a user might 
complain if their disks got weird once an hour.

Regardless, if you don't need optimization why worry? It's like the Pope 
comparing brands of condoms.

Again, we don't excoriate the value of optimizations by citing examples where 
optimization isn't needed. We evaluate optimizations by how useful they are 
when they are needed.

-- 
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg

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O.T. optimising file placement Roedy Green <see_website@mindprod.com.invalid> - 2012-02-21 09:59 -0800
  Re: O.T. optimising file placement Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-02-21 18:05 -0800
  Re: O.T. optimising file placement Jeff Higgins <jeff@invalid.invalid> - 2012-02-21 21:41 -0500
    Re: O.T. optimising file placement Jeff Higgins <jeff@invalid.invalid> - 2012-02-21 23:23 -0500
      Re: O.T. optimising file placement Roedy Green <see_website@mindprod.com.invalid> - 2012-02-22 11:15 -0800
        Re: O.T. optimising file placement Jeff Higgins <jeff@invalid.invalid> - 2012-02-22 16:00 -0500
          Re: O.T. optimising file placement Jeff Higgins <jeff@invalid.invalid> - 2012-02-22 16:03 -0500
            Re: O.T. optimising file placement Gene Wirchenko <genew@ocis.net> - 2012-02-22 14:52 -0800
              Re: O.T. optimising file placement Jeff Higgins <jeff@invalid.invalid> - 2012-02-22 18:24 -0500
                Re: O.T. optimising file placement Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-02-22 17:10 -0800
                Re: O.T. optimising file placement Gene Wirchenko <genew@ocis.net> - 2012-02-22 20:02 -0800
        Re: O.T. optimising file placement Lew <noone@lewscanon.com> - 2012-02-22 14:27 -0800
          Re: O.T. optimising file placement Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-23 01:31 +0000
            Re: O.T. optimising file placement Arne Vajhøj <arne@vajhoej.dk> - 2012-02-22 21:40 -0500
              Re: O.T. optimising file placement Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-23 23:16 +0000
                Re: O.T. optimising file placement Patricia Shanahan <pats@acm.org> - 2012-02-23 16:22 -0800
                Re: O.T. optimising file placement Patricia Shanahan <pats@acm.org> - 2012-02-23 21:45 -0800
                Re: O.T. optimising file placement Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-24 20:21 +0000
                Re: O.T. optimising file placement Arne Vajhøj <arne@vajhoej.dk> - 2012-02-24 20:31 -0500
                Re: O.T. optimising file placement Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-25 13:15 +0000
            Re: O.T. optimising file placement Lew <noone@lewscanon.com> - 2012-02-23 16:39 -0800
              Re: O.T. optimising file placement Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-24 01:49 +0000
                Re: O.T. optimising file placement Lew <noone@lewscanon.com> - 2012-02-24 10:50 -0800
                Re: O.T. optimising file placement Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-24 23:59 +0000
              Re: O.T. optimising file placement Arne Vajhøj <arne@vajhoej.dk> - 2012-02-24 20:25 -0500
    Re: O.T. optimising file placement Roedy Green <see_website@mindprod.com.invalid> - 2012-02-22 10:54 -0800

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